Simulation Program with Integrated Circuit Emphasis (SPICE) is a software program that simulates electronic circuits. Using SPICE, any voltage or current waveform in a circuit can be analyzed. SPICE calculates these voltages and currents versus time or frequency.
Currently, SPICE is available from many vendors who have added schematic drawing tools to the front end and graphics post-processors to plot the results. SPICE simulators and applications have expanded to analog and digital circuits, microwave devices, and electromechanical systems.
SPICE operates by describing a circuit in a text file called a circuit netlist, and then running a simulation. A collection of circuits is typically available for the user of SPICE to retrieve and modify as desired. SPICE reads the circuit netlist and then performs the requested analysis. The results are stored in a text output file or a binary data file. The results of the simulation may be viewed in a text output file using a text editor. Most SPICE programs provide a graphical viewer to plot waveforms stored in the binary data file.
Classification is used to recognize the circuit behavior defined by a netlist. It identifies related transistors that perform an operation such as those performed by logic functions (e.g. AND, OR, NOT, etc.) or state elements (e.g., latches, flip-flops, etc.). The collection of all these operations defines the overall circuit behavior. Classification is especially useful for electrical and logical analysis of custom circuits (transistor-level) in which the netlist hierarchy, if it exists, does not represent the operational hierarchy from which the overall circuit behavior can be determined. These custom circuits are typically found in processors (e.g., central processing units (CPUs), graphics processing units (GPUs), and the like), and most other high-performance integrated circuits (ICs). When rule-based classification (i.e., structure recognition) is used, the circuit netlist is traversed and structures (i.e., circuit patterns) embedded in software are recognized. However, it becomes virtually impossible to fully recognize the circuit netlist as the circuit's complexity increases.
If the rules of recognition are removed from the software, and instead are defined by separate, smaller circuit netlists (templates), a fully extensible classification methodology may be realized. Software recompilation is not required to extend the abilities of the classifier to identify circuits, and classification may easily be enhanced by creating new templates defining the new objects to be automatically identified.